WO2007040034A1

WO2007040034A1 - Composite membrane material for hydrogen separation and element for hydrogen separation employing the same

Info

Publication number: WO2007040034A1
Application number: PCT/JP2006/318411
Authority: WO
Inventors: Hideomi Ishibe; Hiroyasu Taga
Original assignee: Nippon Seisen Co., Ltd
Priority date: 2005-09-30
Filing date: 2006-09-15
Publication date: 2007-04-12
Also published as: GB2445492B; US20100018397A1; GB0806301D0; KR20080047603A; US8226751B2; GB2445492A; KR101280790B1; CN101277752B; JP2007117992A; JP5395322B2; CN101277752A

Abstract

A composite membrane material characterized by comprising: a hydrogen-permeable membrane which is selectively permeable to hydrogen and has been formed by rolling into a thickness of 30 µm or smaller, in which it is difficult for the membrane by itself to retain its shape; and, disposed on either side of the hydrogen-permeable membrane, a shape-retention mesh constituted of a wire made of a material selected among high-melting metals which do not thermally diffuse into the hydrogen-permeable membrane. It is further characterized in that the shape-retention mesh and the hydrogen-permeable membrane have been superposed and pleated in an unbonded state so that they are separable and have a shape in which the hydrogen-permeable membrane has a surface area at least 3 times per unit area. This material is used to constitute an element for hydrogen separation.

Description

Specification

Composite membrane material for hydrogen separation, and element for hydrogen separation using the same

The present invention relates to a composite membrane material for hydrogen separation that can be used to selectively permeate hydrogen gas in a mixed gas containing hydrogen and to be separated with high purity, and for hydrogen separation using the same. Regarding elements.

Background art

[0002] Hydrogen is used as a next-generation energy source, and for its production, for example, a method using electrolysis of water, or various “source gas” powers such as methanol, propane gas, liquefied natural gas, and city gas. It is known how to obtain hydrogen gas depending on the quality. In particular, in the latter case, a hydrogen mixed gas is obtained in which hydrogen gas is mixed by reforming or transforming those gases. However, in order to use hydrogen gas as fuel for power generation, it is necessary to separate 99.99% or higher purity hydrogen gas.

[0003] As illustrated in FIG. 8, for example, a raw material gas that is natural gas, and sometimes the following hydrogen separation process is used. This hydrogen separation process involves desulfurization at 350 ° C desulfurizer a, then introducing reforming steam at 800 ° C reformer b, 400 ° C high-temperature CO converter c, 250 ° Go through low-temperature CO converter d at C and generate hydrogen with PSA (hydrogen purifier by catalyst adsorption) e at a temperature of 100 ° C or less.

[0004] However, in this process using PSA, the reaction equilibrium reaction becomes a high temperature of about 800 ° C. In addition to the complexity and size of the equipment itself, the number of processing steps and the number of equipment will increase, and the equipment costs will be high, making equipment maintenance difficult. However, the purity of the hydrogen gas that can be obtained is also not satisfactory, and this process is expected to improve in terms of the purification efficiency of hydrogen gas, and has not been sufficiently spread.

[0005] In order to improve such a problem, as shown in FIG. 9, in recent years, there is a method of reforming the raw material gas by water steam downstream of the desulfurizer a. After this reforming, high purity hydrogen gas is obtained in the membrane reactor f with a hydrogen separation membrane. Since this system uses a catalyst and is a non-equilibrium reaction, the reforming temperature may be as low as about 550 ° C., for example. Reform For example, when natural gas is used as the source gas, the reaction of CH + 2H 0 → 4H + Co

4 2 2 2 Therefore, it is separated into hydrogen and off-gas (carbon dioxide).

[0006] As described above, hydrogen can be purified and separated from the introduced raw material gas and water vapor in two steps, and the off-gas is taken out and reused, for example, by utilizing its temperature. In this process, the hydrogen separator using the membrane reactor f can be processed at a relatively low temperature. Therefore, it can be greatly reduced in size and simplified as compared with the conventional process apparatus, and can be used as an on-site apparatus for home use or stand use. It is also expected to be used as a high-purity hydrogen generator for fuel cells.

[0007] However, the hydrogen separation element in such an apparatus has a thin hydrogen permeable membrane made of Pd or an alloy thereof, which is known as a metal that selectively permeates hydrogen gas, facing the source gas side. Arrange. This hydrogen permeable membrane is usually supported by a porous support. The hydrogen gas separated by the hydrogen permeable membrane is taken out through the support. Therefore, the support supports the pressure of the supply gas exerted on the hydrogen permeable membrane to prevent deformation of the membrane. It is also used as a flow path member for allowing the hydrogen gas after separation to flow well.

With respect to such a hydrogen separation member, a hydrogen permeable membrane is directly supported on a porous support by a method such as electrolytic plating, electroless plating, or chemical vapor deposition. In this method, for example, Patent Document 1 proposes that the hydrogen separation efficiency (volume efficiency) per unit volume can be increased. In addition, an inorganic porous or organic membrane support having a large number of projections and depressions is formed using a mold prepared by an electroplating method. For example, Patent Document 2 discloses that by forming a separation membrane on the surface of the membrane support by electroless plating, a gas separation membrane having a large surface area and an increased throughput can be obtained.

[0009] Further, a mesh screen is used as the support structure. The hydrogen separation foil is placed on the screen and pressed with a roller or the like so as to follow the uneven surface of the mesh. Moreover, the durability at high temperature and high pressure is improved by fixing these contact surfaces. Further, for example, Patent Document 3 proposes a separation apparatus having high flux capacity and low cost.

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-239353 Patent Document 2: Japanese Patent Laid-Open No. 2001-29761

Patent Document 3: Japanese Patent Laid-Open No. 2001-162144

Disclosure of the invention

Problems to be solved by the invention

[0011] However, the separation membrane according to Patent Document 1 permeates hydrogen through a surface treatment method such as electroless plating or ion plating on the outer surface of a porous support having irregularities on the surface. A film is formed. Therefore, it is difficult to increase the adhesion strength between the porous support and the hydrogen permeable membrane. In addition, partial fatigue failure phenomenon (cracking, peeling of support force, etc.) of the permeable membrane is likely to occur due to repeated expansion and contraction of the separation membrane accompanying absorption and release of hydrogen gas or heating and cooling. Further, since the rough outer surface of the porous support is used, it is difficult to stabilize the quality of the formed permeable membrane and improve the production yield.

[0012] In addition, the one of Patent Document 2 is merely a separation device in which the permeable membrane itself is manufactured to have irregularities and placed on a flat support so that the space between them is a hydrogen gas flow path. On the other hand, the gas separator according to Patent Document 3 has an undulating surface along the texture of the support (wire mesh screen) so that it can follow even when the foil expands and contracts when exposed to a gaseous hydrogen stream. As a method, for example, it is disclosed that pressing or roller processing is performed at a pressure of about 3.1 to 11 tons per lcm ² and then integrated. This technology also combines and integrates the support and the permeable membrane. Due to repeated expansion and contraction of the separation membrane, the partial fatigue failure phenomenon (cracking, etc.) of the permeable membrane caused by this bond cannot be prevented. In particular, since a screen is used as a support, there is a risk of damaging the thin foil material during foil stamping, which may cause new quality defects.

As described above, the gas separation membrane according to each of the above-mentioned patent documents is supported by coupling a support member disposed on the downstream side (secondary side) of the permeable membrane with the permeable membrane exposed on the surface. It is a thing of the structure to do. Therefore, care should be taken to prevent damage to the permeable membrane due to careless handling and supply pressure of the raw material gas, to prevent cracking due to expansion and contraction of the permeable membrane, and to prevent performance degradation due to diffusion that occurs when the permeable membrane contacts the support. Cost. Furthermore, it must have the workability for mounting on machinery. Therefore, these gas separation membranes are not satisfactory. Moreover, the hydrogen permeable membrane is fixed to the support in any case, and it is difficult to recycle only the permeable membrane when discarded.

[0014] Therefore, according to the present invention, in a thin hydrogen permeable membrane that is difficult to maintain its shape against a gas supply pressure by itself, a shape retaining mesh made of a refractory metal is laminated in a non-bonded state along the permeable membrane. Forms corrugation folds. This increases the hydrogen permeation amount per unit area and prevents defects such as cracks in the permeable membrane due to heating and cooling. Another object of the present invention is to provide a high-quality, long-life composite membrane material for hydrogen separation that can improve the recyclability of only expensive hydrogen-permeable membranes, and a hydrogen separation element using the membrane material.

Means for solving the problem

[0015] The invention of claim 1 is

A hydrogen permeable membrane that selectively permeates hydrogen;

A retaining mesh disposed on at least one side of the hydrogen permeable membrane to retain the hydrogen permeable membrane;

The hydrogen permeable membrane is rolled to a thickness of 30 m or less, which makes it difficult to maintain the shape by itself, and the shape retaining mesh does not cause heat diffusion with the hydrogen permeable membrane! /, Selected from refractory metals Made of metal wire,

A combination of the hydrogen permeable membrane and the shape retaining mesh, and a fold folding process for continuously providing folds,

By this folding process, the ratio SZSo of the area So of the reference surface at the average height passing through the center of the height of the fold of the hydrogen permeable membrane to the surface area S of the hydrogen permeable membrane in the reference surface is 3 to It is a composite membrane material for hydrogen separation characterized by being molded 10 times.

[0016] In the invention according to claim 2, the refractory metal of the shape retaining mesh is a metal wire having a melting point of 2,000 ° C or more, and the invention according to claim 3 is characterized in that the shape retaining mesh is The refractory metal is formed of a molybdenum metal wire having a wire diameter of 0.3 mm or less. The invention according to claim 4 is characterized in that the fold has a peak height H of 5 mn in its transverse cross section. ! It is characterized in that the pitch P, which is a straight line connecting the centers of the heights of adjacent folds to ˜30 mm, is set to be 0.8 times or less of the peak height.

[0017] The invention according to claim 5 is a compound for hydrogen separation according to any one of claims 1 to 4. This is an element for hydrogen separation using a composite membrane material. A porous inner cylinder; a composite membrane material for hydrogen separation that is fitted on the porous inner cylinder and folded at a predetermined pitch; and a porous outer cylinder that encapsulates the composite membrane material. It is characterized by.

[0018] In the invention according to claim 6, the porous outer cylinder and Z or the porous inner cylinder are formed of either a punching plate or a wire mesh, and the invention according to claim 7 is at least one of A connecting joint is provided on the end face of the substrate, and the invention according to claim 8 is characterized in that the hydrogen separation membrane is formed on the primary side where the mixed gas before the permeation of hydrogen flows and the porous outer surface. The catalyst is arranged in a non-contact state through the shape retaining mesh in a space between the tube or the porous inner tube and the shape retaining mesh.

The invention's effect

The present invention according to claim 1 uses a membrane-shaped hydrogen permeable membrane that cannot withstand the supply pressure of the source gas alone and whose shape is difficult to maintain. A shape-retaining mesh is laminated and reinforced along this hydrogen permeable membrane, and laminated in a non-bonded state that does not cause bonding due to heat diffusion. Furthermore, the hydrogen separation permeation area ratio is increased to a large area of 3 to LO times. Increased by folding. Therefore, this fold shape can be effectively maintained, and the hydrogen separation efficiency can be greatly improved. Since the shape-retaining mesh uses a refractory metal, it is possible to prevent influences such as diffusion with the filled catalyst powder and other metal members and resulting performance degradation. In addition, it is a long-life, high-precision composite membrane material that can be used effectively for hydrogen separation.

In the present invention, the mesh and the hydrogen permeable membrane are laminated and formed in a non-bonded state. For this reason, even when the hydrogen permeable membrane itself expands and contracts with heating and cooling when using it, it can be displaced relatively freely, and the occurrence of defects such as cracks and cracks can be suppressed. In addition, since both are simply laminated in a non-bonded state, only the expensive hydrogen permeable membrane can be easily separated and recovered and reused.

In addition, the hydrogen permeable membrane may be a thin film material obtained by rolling a plate material or a block piece to a predetermined thickness. Therefore, it is a high-quality thin film material having a uniform quality and having no voids as compared with the case of a thin film formed by a conventional method such as a plating method.

[0022] Further, according to the inventions of claims 2 to 4, the shape-retaining mesh is composed of a metal wire having a melting point of 2000 ° C or higher, and the difference from the hydrogen permeable membrane is large. Heat diffusion Can be prevented. Thereby, it is possible to prevent a decrease in hydrogen separation characteristics of the membrane material. In particular, the shape-retaining mesh made of molybdenum metal has a feature that the spring back is small when the crease processing is performed while having sufficient rigidity. As a result, it is possible to easily impart a fold shape to the hydrogen permeable membrane, and the hydrogen permeable membrane can be supported with great elasticity after shaping. Therefore, this formability makes it possible to use thinner wires. Therefore, a sufficient gas flow path can be provided, the reaction area on the surface of the hydrogen permeable membrane can be increased, and a large fold shape can be set.

[0023] Further, according to the invention of claim 5, the composite membrane material for hydrogen separation folded at a predetermined pitch is attached to the outer peripheral surface of a porous porous inner cylinder. Further, on the outside, a porous outer cylinder is concentrically wrapped. As a result, when the effective treatment area per unit area is increased! /, In addition to the above-described effects of the composite membrane material, the composite membrane material is firmly supported by the porous inner cylinder. Further, since the surface is encapsulated by the porous outer cylinder, the surface of the thin composite film is not exposed and handling is easy. Achieves miniaturization of the element itself and greatly improves hydrogen separation performance. In the present invention, it is also possible to carry out the present invention at a low cost and a light weight, which is used in the case of a conventional plating process and requires the use of an expensive porous sintered body.

[0024] Further, according to the inventions of claims 6 to 7, the porous inner cylinder and the porous outer cylinder can also be constituted by a punching plate or a coarse metal mesh which is a perforated steel plate. This makes it possible to provide an inexpensive element for hydrogen separation. The composite membrane material is provided with the shape retaining mesh using a high melting point metal on the surface thereof. Therefore, even when the composite membrane material is in direct contact with the porous inner cylinder and the porous outer cylinder, the hydrogen permeable membrane itself is isolated from them by the mesh. Therefore, there is an advantage that interdiffusion between these members and accompanying characteristic deterioration can be prevented. Further, as in the invention of claim 7, by providing a connecting joint on one end face in the length direction, it can be easily attached to the apparatus main body. For example, a plurality of these devices can be connected to form a large capacity type device. Further, as in claim 8, the hydrogen separation performance is enhanced by arranging the catalyst on the primary side. Further, since the catalyst does not come into contact with the separation membrane, the heating reaction is suppressed and the life is prevented from being shortened.

Brief Description of Drawings FIG. 1 is an enlarged partial sectional view of a composite membrane material for hydrogen separation according to the present invention.

FIG. 2 is a plan view showing an enlargement of the hydrogen permeable membrane 1000 times.

FIG. 3 is a front view showing the upper half of the hydrogen separation element in cross section.

FIG. 4 is a sectional view of the trunk.

FIG. 5 is an enlarged cross-sectional view of a trough when catalyst powder is used.

FIG. 6 is a front view showing a cross section of the upper half of one embodiment of the hydrogen separation element.

FIG. 7 is a cross-sectional view showing an example of a membrane former formed by arranging a plurality of modules in which a plurality of hydrogen separation elements are connected in parallel.

FIG. 8 is a block diagram illustrating a conventional hydrogen production process.

FIG. 9 is a block diagram illustrating a hydrogen production process using a membrane reactor. Explanation of symbols

[0026] 1 Composite membrane material

2 Hydrogen permeable membrane

3 shaped mesh

10 Hydrogen separation element

11 Porous inner cylinder

12 porous outer cylinder

15 end fitting

15A fitting bracket

15B sealing bracket

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged cross-sectional view showing a part of a composite film material 1 according to the present invention. In the present embodiment, a hydrogen permeable membrane 2 that selectively permeates hydrogen gas and a shape retaining mesh 3 disposed on the inner and outer surfaces of the hydrogen permeable membrane 2 are provided. This shape-retaining mesh 3 is woven with a refractory metal wire w. The hydrogen permeable membrane 2 and the shape retaining mesh 3 are laminated in a non-bonded state. In addition, both of them are formed into a corrugated shape having ridges 5 and 5 extending in a certain direction (the length direction in the present embodiment) by folding into a predetermined shape. The hydrogen permeable membrane 2 is selected from metal materials having hydrogen permeation performance such as Pd metal, Pd—Cu or Pd—Ag Pd alloy. The thickness is 30 μm or less (for example, 2 to 30 μm, preferably 5 to 20 μm), which is difficult to maintain the shape by itself. The hydrogen permeable membrane 2 may be a rolled membrane formed by pressing a plate material, block, or the like by a method such as rolling or pressing.

[0029] It has been conventionally known that these Pd metals and Pd alloys have a function of selectively permeating only hydrogen. The principle is described in various literatures including the scientific journal “Functional Materials” (2003 No. 4, P76 to 87). When the hydrogen molecule comes into contact with the Pd film, at that moment it dissociates into a hydrogen atom and ionizes, passing through the Pd film as a proton. When it reaches the back side, it is supposed to become a hydrogen molecule by combining with electrons.

[0030] Further, in order to promote such a phenomenon and improve the hydrogen permeation performance, durability, hydrogen embrittlement resistance, etc.! / Soot is improved in workability and the like, the Pd metal is, for example, 10% by mass or more (preferably 20% Pd alloys containing up to 50%) Cu, Ag, or Au can be used. For other purposes, a trace amount of a third element may be added in combination. In this case, the third element is at least one selected from group VIII elements such as Pt, Rh, Ru, In, Fe, Ni, and Co, or via group elements such as Mo, and is 5% or less. Note that the Pd—Ag alloy containing, for example, 20 to 45% Ag has improved hydrogen permeation performance. Pd-Cu alloys can improve durability as well as hydrogen permeation performance by using a membrane material containing 35-45% Cu. Further, as other film materials, for example, those having V-based or V-Ni-based metal force, or amorphous film materials can be used. The type and form of the metal composition can be arbitrarily selected as necessary.

[0031] In order to improve the hydrogen permeation performance, it is usually recommended that the molding film thickness be as thin as possible to shorten the permeation time. However, when using a thin film material with a thickness that is thinner than necessary, there is a concern that microscopic inevitable pinholes directly affect the separation accuracy. As a measure for preventing the pinholes and the like, when using the metal material plate material and the block rolled material as a raw material, the internal pores can be reduced to reduce the size. When dissolved, inevitable impurities are reduced so that, for example, non-metallic inclusions are not generated. For this purpose, cold crucible is used as a dissolution method. It is desirable to adopt a high purity melting method such as vacuum melting or double melt method. Usually it is set to a thickness of at least 2 m.

[0032] Thus, the quality of the hydrogen-permeable metal hydrogen-permeable film 2 is extremely important.

In particular, the thin film material formed by rolling can improve mechanical properties such as elasticity and toughness as well as structural stability by the processing, and can suppress the occurrence of defects such as pinholes. For example, Fig. 2 shows the state without defects. Fig. 2 is a diagram in which the metal structure on the surface of the hydrogen permeable membrane heat-treated at 1050 ° C is magnified 1000 times by repeatedly rolling and heat-treating it to a thickness of 20 m. As can be seen from this figure, the crystal grain size has an equivalent diameter of about 6 to 20 m, and has a very stable structure. The equivalent diameter is a value obtained from the cross-sectional area on the assumption that the crystal grains are circular.

[0033] Such a membrane material is preferable since it has good hydrogen permeation performance. However, since it is difficult to maintain a predetermined film shape with a single thin film, in the present invention, it is combined with the shape retaining mesh 3 in a non-bonded state (metallic) and subjected to predetermined corrugation. Features.

That is, even if the hydrogen permeable membrane 2 has rigidity and elasticity, the shape retaining mesh 3 can maintain a fold shape. The two are combined in a non-bonded state. Therefore, even when the hydrogen permeable membrane 2 itself expands or contracts due to the heating or cooling, it can be displaced relatively easily without restriction. Further, the possibility of occurrence of pinholes and cracks in the hydrogen permeable membrane 2 can be reduced, and the surface area ratio per unit area can be increased by scoring as described above.

[0035] The shape-retaining mesh 3 used in this way is made by weaving a wire w using a refractory metal having a melting point higher than that of the hydrogen permeable membrane 2, for example, 1800 ° C or higher, preferably 2000 ° C or higher. The mesh 3 is disposed on at least one side of the hydrogen permeable membrane 2. In the form shown in Fig. 1, they are arranged on both sides. This one side is the primary side of the hydrogen permeable membrane 2 (the side into which the fluid to be treated flows is called the primary side!), Or the secondary side (the outflow side is called the secondary side). You can also In this embodiment, the shape retaining meshes 3A and 3B are provided on both sides, that is, the primary side and the secondary side, respectively, so that the shape of the fold 4 is efficiently and reliably held. If necessary, the shape retaining mesh 3 is provided only on the secondary side of the separation membrane 2 to ensure its support. In addition, as a specific configuration of the shape retaining mesh 3, for example, the wire diameter is 0.05 to 0.4 mm. With a fine wire of about 30 to: A net material that is plain or twilled to about LOO # can be used. For the shape retaining mesh 3, other materials such as knitting and expansion mesh can be used. As for the mesh opening, the function of molding, the support performance of the hydrogen permeable membrane 2, and the function as a covering for holding the various powders when filled with various powders in contact with the shape retaining mesh 3. You can choose from.

[0036] Such a metal material having a high melting point prevents mutual diffusion with the hydrogen permeable membrane 2 in contact therewith. In addition, it prevents mutual diffusion with the catalyst powder described later when used as a hydrogen separation element. Even when heated in contact with the hydrogen permeable membrane 2 and the catalyst powder, mutual diffusion between the two can be prevented, thereby preventing performance degradation. Moreover, since the shape-retaining mesh 3 is a metal material, the mesh formation can be easily performed, and since it has sufficient flexibility, it is suitable as a shape-retaining member.

[0037] Specific examples of the refractory metal include metals such as molybdenum, vanadium, niobium, chromium, and tantalum, as well as some third elements (for example, W, YO of 10 mass% or less). ) Is selected. Especially the molybdenum or moly

twenty three

The mesh using a Buden alloy has a very high melting point of about 2600 ° C., and the difference in melting point from the hydrogen permeable membrane 2 is 1000 degrees or more. Therefore, mutual diffusion between the two can be reliably prevented and performance degradation can be suppressed. In addition, its mechanical properties, for example, have a high coefficient of elasticity of about 250,000 to 350, OOON / mm ^{2 and} a yield strength of about 400 to 600 N / mm ² even in the soft state. Therefore, when forming with pleats, it can be shaped easily with less spring back, and the shape can be maintained with great elasticity for maintaining the shape after formation. Therefore, it is excellent as a shape-retaining mesh 3 such that a thinner wire can be used. It also has a high temperature strength at a working temperature of about 550 ° C.

[0038] The hydrogen permeable membrane 2 and the shape retaining mesh 3 are laminated in a non-bonded state as described above, and the laminated membrane material of the present invention is formed by creping the laminated body at a predetermined pitch. 1 is configured.

[0039] The number, shape, and size of the folds 4 can be set as appropriate in terms of quality characteristics such as use, hydrogen separation conditions, and thickness of the hydrogen permeable membrane 2. In the present invention, the permeation 4 is added to increase the hydrogen permeation area. In addition, it has a shape that can resist the hydrogen mixed gas supplied with pleats. . This prevents buckling deformation of the folds. Therefore, the ratio (SZSo) with the surface area S of the hydrogen permeable membrane 2 per area So of the reference plane passing through the center position of the peak height of the fold 4 is set to 3 times or more and 10 times or less. As a result, the effective transmission area can be increased. In the present specification, “surface area S” means the permeation area of the permeation membrane 2. When the pleats 4 are all the same shape including the peak height H, the ratio (SZSo) is, for example, in FIG. 1, the pitch length of the arc between the pitch points at the center of the peak height, It can be obtained as a ratio of the lengths between the pitches P and the ratio of the cross-sectional lengths of the permeable membrane 2. The pitch length of the arc is the value obtained by converting the pitch P, which is the straight line length between the pitch points at the center of the peak height, into an arc.

[0040] As for the "reference plane", in the case where the pleated hydrogen permeable membrane 2 is formed in a cylindrical shape as shown in FIGS. 1 to 4, for example, the center of the peak height is set to a radius. And the circumferential surface. On the other hand, even when the permeable membrane 2 is formed into a flat plate shape, the surface passes through the center of the height of the peak portion in the same manner as described above. In this case, since the shape is planar, the unit area on the plane is used regardless of the crease.

Furthermore, for the average height in the case of non-uniform shapes, such as the height of each fold 4 being different, for example, folds of 1Z4 or more of the total number of folds are arbitrarily extracted, and more preferably, all the folds are It is shown by the average value of the measured height.

[0041] As an example of the size of the fold when the folds having the same shape are formed, one having a ridge height H of 5 to 30 mm and a pitch P of about 3 to 30 mm can be used. More preferably, the pitch P is set to about 0.8 times or less (preferably 0.2 to 0.7 times) of the peak height H. In this case, the “peak height H” is the height to the peak force valley bottom point of the peak 4 of the hydrogen permeable membrane 2 (in the case of FIG. 1, the height in the radial direction). On the other hand, as described above, “pitch P” is a straight line length between the height center positions (pitch points) of the ridges where two adjacent folds 4 correspond to each other.

[0042] When the ratio is less than 3 times, as described above, the hydrogen permeation reaction area is not sufficiently increased. In addition, when the pleat 4 is flat and incorporated, for example, the shape may not be sufficiently maintained with respect to the pressure of the supply gas during use. Also, when the ratio exceeds 10 times, the rise of the fold 4 becomes abrupt and there is a problem that the supply gas does not enter sufficiently between the folds. Preferably, 4 to: LO times, more preferably 4 to 8 times.

[0043] The composite membrane material 1 of the present invention is a material in which the hydrogen permeable membrane 2 and the shape retaining mesh 3 thus configured are overlapped and creased at a predetermined pitch. In addition to being used as a flat plate as it is, for example, as shown in FIG. 3 and FIG. 4, it can be used as a cylindrical body with a pleat such as a cylindrical shape or a rectangular shape. For this purpose, at both ends, they are butted or overlapped with other members and are tightly coupled. The shape and dimensions are arbitrarily set. Although not shown in the drawings, the flat plate is a flat plate in which, for example, two sheets are overlapped with a gap, and the outer peripheral edge is closely closed using a frame inserted into the gap, and integrally joined. A hollow element can be used. A through hole for injecting raw material gas or taking out hydrogen gas is formed in the frame. As a method for bonding the permeable membrane 2 (or the composite membrane material 1) during the molding and assembling, for example, a heat bonding method such as welding or brazing is preferred, and brazing can be performed relatively easily. In addition, it has a high sealing property and can be combined.

FIGS. 3 and 4 show an example of the hydrogen separation element 10 using the composite membrane material 1 formed into such a cylindrical shape with reference to FIG. Porous inner cylinder 11 in which a punching plate is formed in a cylindrical shape, porous outer cylinder 12, a fitting metal 15A as an end fitting 15 fixed to one end thereof, and a sealing as an end fitting 15 closing the other end Use bracket 15B. Therefore, for example, the porous inner cylinder 11 is densely inserted into the inner hole of the composite membrane material 1, and the sealing fitting 15B is arranged concentrically. The inner surface of the sealing metal fitting 15B and the facing end surface of the composite film material 1 are welded without causing leakage. The composite film material 1 can also be airtightly bonded to the inner surface of the sealing metal fitting 15B by heating from the outer surface of the sealing metal fitting 15B. At this time, the porous inner cylinder 11 and the porous outer cylinder 12 may be welded in advance to the inner surface of the sealing metal fitting 15B.

[0045] In this example, the joint fitting 15A also has a force with the inner member 15a, the ring-shaped outer member 15b, and the base member 15c. The inner member 15a is welded to the porous inner cylinder 11 and the end faces of the composite membrane material 1 facing each other. The outer member 15b also has a ring strength that is joined to the flange of the inner member 15a and closes the gap between the porous outer cylinder 12 and the outer member 15b. The base member 15 c can be joined to the inner member 15 a to form an extraction hole 17 that communicates with the inner hole of the porous inner cylinder 11. The base member 15c is provided with a hexagonal nut portion and an external thread portion for connection. These are assembled together, for example, by welding each joint. In such a configuration, the mixed gas for raw material containing hydrogen to be supplied is introduced from the opening 12 A provided in the porous outer cylinder 12 as shown by an arrow in FIG. Only the hydrogen separated by the hydrogen permeable membrane 2 is taken out from the opening 11A of the porous inner cylinder 11 and fed to the next step from the take-out hole 17 of the fitting 15A. The mixed gas of the raw material can be supplied in the opposite direction, that is, from the porous inner cylinder 11 toward the porous outer inner cylinder 12 side. In the present invention, when the hydrogen gas is taken out from the hole 17, the mixed gas is reformed in the primary side of the composite membrane material 1, that is, in the gap between the composite membrane material 1 and the porous outer cylinder 12. It is also possible to arrange a reforming catalyst 20 for this purpose. Further, as schematically shown in FIG. 5, the gap between the secondary side of the composite membrane material 1 and the porous inner cylinder 11 can also be filled. At this time, the reforming catalyst 20 functions as a support material 22 for supporting and retaining the shape of the composite membrane material 1. Note that alumina powder or the like can also be used when used simply as a support material 22 for support and shape retention.

[0047] Further, for the attachment between the end fitting 15, the composite membrane material 1, the porous inner cylinder 11, and the porous outer cylinder 12, for example, welding can be employed in addition to the brazing method. Ginguchi can be used for brazing. For example, the porous inner cylinder 11 and the composite membrane material 1 fitted to the porous inner cylinder 11 are set between the inner member 15a of the joint fitting 15A and the sealing fitting 15B and brazed to each other. Further, one end of the porous outer cylinder 12 is attached to the sealing metal fitting 15B. As a result, a gap is formed between the other end portion of the porous outer cylinder 12 and radially outward of the inner member 15a. In addition, a vacant space is formed in the porous outer cylinder 12 and the vacant chamber is filled with the catalyst powder 20. Thereafter, the ring-shaped outer member 15b and the base member 15c are attached and sealed.

[0048] The silver wax has a relatively low melting point and does not need to be heated at a high temperature, and since silver has the basic composition of the hydrogen permeable membrane 2 itself, it does not substantially impair the hydrogen permeation performance. Further, the shape and structure of the end fitting are merely examples, and include various shapes and structures that have been practiced in the past other than the above description and do not restrict the invention as a whole.

[0049] The dimensions and shape of the hydrogen separation element 10 can be set in consideration of its use conditions and installation space. Usually, for example, an outer diameter of 5-30 cm and a length of 5-50 cm This is relatively easy to use, but is not limited to this, and various dimensions and non-circular shapes such as a square cross section can be changed as necessary.

In the present embodiment, the porous inner cylinder 11 and the porous outer cylinder 12 are formed by forming a perforated steel plate such as a punching plate into a cylindrical body having a circular cross section. Instead of this, for example, various types of porous cylindrical bodies such as woven wire nets, expanded metal, and other metal porous sintered bodies can be used. In particular, the former perforated steel sheet is easily used because it is inexpensive in price and has sufficient strength and opening. However, when the sintered molded product such as the latter metal powder is used for the porous outer cylinder 12, for example, it functions as a prefilter member for removing in advance the impurity particles in the supplied hydrogen mixed gas. For this purpose, for example, a sintered body using metal powder of about # 140Z200 to 200Z250 or metal fiber having a fiber diameter of about 10 to 30 μm can be used.

Thus, the porous inner cylinder 11 and the porous outer cylinder 12 are used as necessary. Therefore, as shown in this embodiment, both can be formed of the same kind of perforated steel plate. Either the porous inner cylinder 11 or the porous outer cylinder 12 can be used as another member such as the sintered compact. The sizes of the openings 11A and 12A provided in the porous inner cylinder 11 and the porous outer cylinder 12 are, for example, such that gas fluid can freely pass therethrough and the catalyst powder 20 and the composite membrane material 1 are held. Further, as described above, the porous outer cylinder 12 can be made into a sintered body to have a filtration function. In some cases, a finer mesh or the like is provided on the inner side of the porous outer cylinder 12 so as to securely hold the catalyst powder.

[0052] The porous inner cylinder 11 and the porous outer cylinder 12 have a metal that does not react with a hydrogen mixed gas or the like to be treated even when the hydrogen permeable membrane 1 or the catalyst powder 20 is heated. Material is selected. For example, stainless steel, cobalt alloy, titanium alloy and the like having excellent hydrogen embrittlement resistance can be used relatively suitably. Stainless steel, particularly austenitic stainless steel with a nickel equivalent of 26% or more (preferably 27 to 30%) is also effective. Also, it can be preferably used because it is relatively easy to process such as welding and brazing and has excellent corrosion resistance.

[0053] The nickel equivalent is shown as indicating the stability of austenite. For example, the following formula force can be obtained.

Ni equivalent = Ni + 0. 65Cr + 0.98Mo + l.05Mn + 0.35Si + 12. 6C [0054] In this embodiment, the shape retaining mesh 3 provided on the primary side of the hydrogen permeable membrane 2 is in direct contact between the porous outer cylinder 12, the catalyst powder 20 filled on the secondary side, and the hydrogen permeable membrane 2. To prevent that. As shown in FIG. 5, when the shape retaining mesh 3 is used on both sides of the primary side and the secondary side, as described above, the secondary side of the hydrogen permeable membrane 2 and the porous inner side are not porous. The support material 22 can also be filled in the gap between the cylinder 11.

[0055] When the catalyst powder 20 is filled, the porous outer cylinder 12 has a slightly larger diameter as in this embodiment. As a result, the catalyst powder 20 is also filled in the gap between the crests of the fold 4 and the gap between the crest tip and the porous outer cylinder 12. As a result, the fold 4 has a central force that is directed outward and is expanded by Φ.

[0056] Thus, in the present invention, the catalyst powder 20 can be used as necessary. The specific type and quantity are also set arbitrarily. For example, if the source gas is hydrocarbon, the catalyst powder 20

CH + 2H 0 → 4H + CO and in methanol, CH OH + H 0 → 4H + CO

React with 4 2 2 2 3 2 2 2 respectively. The separated H gas is selectively separated through the hydrogen permeable membrane 2.

2

The Usually, as the catalyst powder 20, for example, a particle-like body having a particle size of several hundreds / zm and a size of about several mm is used. Specific examples thereof include those containing a Group VIII metal such as Fe, Co, Ni, Ru, Rh, and Pt, and NiO. The amount is adjusted in consideration of the type and form of the raw material gas and catalyst powder, as well as the raw gas supply processing conditions.

In the hydrogen separation element 10 of FIG. 3, for example, instead of the sealing fitting 15B described above, a receiving fitting 15C having a screw hole 21 can be used as shown in FIG. The screw hole 21 of the receiving fixture 15C can be screwed into the screw of the fitting 15A. Further, instead of the sealing fitting 15B, an end fitting for communicating by directly welding the end fittings 15 may be used. Further, as shown in FIG. 7, for example, a module in which a plurality of the elements 10 are connected is formed. A plurality of the modules are mounted side by side on one large end plate, and the whole is housed in one large-diameter tube 25. As a result, each element is piped to form a large-capacity membrane reformer for hydrogen separation and separation. [0058] Further, for example, only those with general ring-shaped end fittings attached to both end faces of the element 10 are stocked as standard products. Thereafter, if necessary, other metal fittings for connection and sealing can be used as the attachment element 1 each time if necessary. Also, by prefilling the catalyst powder 20 and the support material 22, the inventory management of the element is facilitated. It can also be connected as shown in Fig. 6. Also, as shown in Fig. 7, it is possible to make a large-capacity hydrogen separation member by connecting hydrogen separation elements. For this reason, as a small and simple high-purity hydrogen generator, it can be used in various fields such as the fuel cell, semiconductor industry, and optical fiber manufacturing.

[Example 1]

A hydrogen permeable membrane was obtained from Pd — 25% Ag metal foil of width lOOmm x length lm that was cold-rolled to a thickness of 20 μm and heat-treated at 1050 ° C. On both sides, a shape-retaining mesh (# 100) made of molybdenum fine wire with a wire diameter of 0.2 mm was laminated, and the laminate was set in a crease forming machine. Then, continuous folds with a peak height of 20 mm and a center pitch of 6.5 mm were formed on these three laminates to create a pleated composite membrane material. The Pd—Ag alloy is 99.91% pure by vacuum melting, and the raw material is an alloy plate that is processed by repeated rolling and heat treatment.

[0060] In this state, the hydrogen permeable membrane and the shape retaining mesh are in close contact with each other although they are in a non-bonded state. It was easy to apply a pleated shape with little rebound of spring force and spring force. Also, in this state, the membrane material has elasticity as a whole, and it is possible to maintain a strong pleated shape that cannot be obtained with only a hydrogen permeable membrane. In addition, the surface of the hydrogen permeable membrane has a good surface state that does not transfer marks such as the mesh texture.

[0061] Next, the front and rear end portions (opposing end portions) of the laminated material were overlapped with each other, and brazing was performed by placing an Ag brazing material having a thickness of 0.5 mm and a width of 2 mm therebetween. As a result, a cylindrical product having the folds in the axial direction was formed. In this brazing portion, the brazing material was completely filled in the gap between the mesh and the hydrogen permeable membrane and joined without leakage.

[0062] This cylindrical product is used as the composite membrane material, and is fitted into a porous inner cylinder having a length of 32 mm and a thickness of 2 mm, made of stainless steel (S US316L), and having a length of 100 mm. Three As shown in Fig. 4, hydrogen separation element is manufactured by attaching a porous outer cylinder (outer diameter 80mm) made of the same perforated plate, joint fittings, and sealing fittings, and then brazing them together. did.

[0063] In this state, since the transmission area of the membrane material itself is 0.1 lm ² and the fold height is 20 mm, this surface area is determined by taking the center point of the fold height of the membrane material as the radius. It had a surface area of 6.1 times. Therefore, seven modules with these four elements connected were set as shown in Fig. 7 and housed in a housing container with an outer diameter of 260mm x length of 460mm to create a hydrogen separator for 20Nm ³ ZH. The reformer volume was 0.024 m ³ .

[0064] (Comparative example)

Pd—25% Ag metal foil with a thickness of m is coated on the surface of a porous support with an outer diameter of 35 mm and a length of lm so that it becomes a membrane reformer for 20 Nm ³ / H as in the previous example. The product was designed to be housed in a container with an outer diameter of 300 mm and a length of 1000 mm. Since the volume of the reformer was 0.078 m ³ , the volume ratio was 1 / 3.2, which was achieved by using the pleated structure according to the present invention.

[Test 1] Hydrogen permeation and thermal cycle test

For both separators, hydrogen permeation is performed for 1 H under the conditions of heating temperature 600 ° C and differential pressure 0. IMPa. After that, the process of cooling by substituting with N2 gas was repeated 100 times in total, and the occurrence of cracks in the hydrogen permeable membrane due to the temperature rise and fall was investigated. As a result, the hydrogen permeation amount per unit element is l lZmin, respectively, and the characteristics with a purity of 99.99% or more are obtained. Further, there was no leakage of the N2 gas with respect to the presence or absence of cracks in the hydrogen permeable membrane. It was confirmed that defects such as cracks did not occur in this example product. This was presumed to be because the hydrogen permeable membrane was disposed in a non-bonded state between the shape retaining meshes and could be displaced in a relatively free state.

[0066] (Test 2) Diffusion generation confirmation test

In addition, in order to confirm the presence or absence of diffusion associated with the thermal cycle test in Test 2, an aging analysis of each metal element in the thickness direction was performed on a sample obtained by disassembling each device element and excising the hydrogen permeable membrane. As a result, the product of this example is isolated by the shape retaining mesh. Since the mesh is a refractory metal, it was confirmed that diffusion to the hydrogen permeable membrane can be prevented and the initial composition ratio is maintained.

Claims

The scope of the claims

[1] A hydrogen permeable membrane that selectively permeates hydrogen,

By this folding process, the ratio SZSo of the area So of the reference surface at the average height passing through the center of the height of the fold of the hydrogen permeable membrane to the surface area S of the hydrogen permeable membrane in the reference surface is 3 to

A composite membrane material for hydrogen separation characterized by being molded 10 times.

[2] The composite membrane material for hydrogen separation according to claim 1, wherein the refractory metal of the shape retaining mesh is a metal wire having a melting point of 2000 ° C or higher.

[3] The composite membrane for hydrogen separation according to [2], wherein the refractory metal of the shape retaining mesh is formed of a molybdenum metal wire having a wire diameter of 0.3 mm or less. material.

[4] The fold has a peak height H of 5 mn in its cross section! The pitch P, which is a straight length connecting the centers of the heights of adjacent folds to 30 mm, is not more than 0.8 times the height of the ridges. The composite membrane material for hydrogen separation as described.

[5] An element for hydrogen separation using the composite membrane material for hydrogen separation according to any one of claims 1 to 4,

A porous inner cylinder, a composite membrane material for hydrogen separation externally fitted to the porous inner cylinder, and a porous outer cylinder enclosing the composite membrane material on the outside,

A hydrogen separation element, wherein the strong porous inner cylinder, the composite membrane material, and the porous outer cylinder are arranged in a concentric length direction.

6. The hydrogen separation element according to claim 5, wherein the porous outer cylinder and the Z or porous inner cylinder are formed of either a punching plate or a wire mesh.

7. The hydrogen separation element according to claim 5 or 6, wherein the hydrogen separation element is provided with a connecting joint on at least one end face in the length direction.

[8] The hydrogen separation membrane has the shape retaining shape in a space between the porous outer tube or the porous inner tube on the primary side into which the mixed gas before permeating hydrogen flows and the shape retaining mesh. The element for hydrogen separation according to any one of claims 5 to 7, wherein the catalyst is disposed without contacting the catalyst with the hydrogen separation membrane through a mesh.